Phenobarbital, a barbiturate, is used to control epilepsy (seizures) and as a sedative to relieve anxiety. It is also used for short-term treatment of insomnia.

Phenobarbital is well known for its long history of use, low cost, and effectiveness. It stays in the body for a long time, so the amount of medicine in the blood stays fairly steady even if it is taken only once a day.

However it also makes many people sleepy and sometimes causes other changes in behavior. Not everyone is affected the same way, however, and many individuals do well when they take phenobarbital. Another problem is that after people take it for a while, they must be very careful if they want to stop taking it. They could have withdrawal seizures. The physician should recommend a very slow reduction in the dose to prevent these seizures.